[Jellby]

OK, here is a more or less working version (no help message yet, and default demo icon).

Some issues I have:

- The "View log" does not look disabled, although I use setEnabled(False). It's not clickable by default, but at least in my computer it's not greyed-out or anything.

- I don't know what to do with the print statements. I'd like them to be off by default, and only appear with some minimal debug level. Better yet, I'd like to have some status indication... can I use some calibre function for that or should I have it inside the plugin?

- In the configuration dialog, is there any way to have the "Restore defaults" button together with OK and Cancel?

- The output PDF is still created in a temp dir, I'd like to add an option to choose whether it should be added to the library or saved to disk elsewhere. Can I use any calibre functions for that? In one case, I'd add a file to the existing book record, and I guess calibre would take care of everything. In the other case I'd probably like to use the "save to disk" template at least.